HISTOLOGICAL EVALUATION OF AUTOLOGOUS CHONDROCYTE TRANSPLANTATION IN THE KNEE

Abstract

This prospective study analyses the histological results of autologous chondrocyte transplantation in patients with articular cartilage defects of the knee joint. Chondrocytes from a non-weight bearing area of the knee were harvested and then cultured in vitro.

Re-implantation involved injection of the chondrocytes into the defect, which was then sealed with a collagen membrane. One year post-op, patients were evaluated by clinical, arthroscopic and histological assessment. A biopsy of the transplanted region was examined by staining with Erlich’s H& E and Safranin 0, polarised light microscopy and by analysis with S100 and immunohistochemistry. Hyaline cartilage content was further assessed by examination of Type IIa & lIb collagen mRNA expression using in-situ hybridisation.

The median age was 31 years. 63 knees were treated. Solitary lesions were treated in 61 knees with two defects being treated in three knees (66 defects in total). The defects were located on the medial femoral condyle in 39 cases, lateral femoral condyle in 14, trochlea in 2 and patella in 11. The defect size ranged from 1–7 cm2 (mean area 3cm2 ). 40 patients had at least one-year follow-up. Using the Brittberg Rating, 11 had excellent results, with 15 good, 10 fair and 4 poor. The mean Lysholm and Gillquist scores improved from 44 pre-op to 77 one-year post-op. Biopsy at one year conftrmed the presence of hyaline cartilage in 22 out of 32 cases (69%). In-situ hybridisation confirmed the presence of Collagen type II in the deep zones of the biopsy with a fibrocartilaginous appearance superficially.

Conclusion: This technique can provide an effective treatment for cartilage defects. The histological results are encouraging and chondrocyte transplantation may be the only procedure to allow regeneration of hyaline like articular cartilage.